import numpy as np
import cv2 as cv
from matplotlib import pyplot as plt

img = cv.imread('in.png', cv.IMREAD_UNCHANGED)
b,g,r,a = cv.split(img)
img2 = cv.merge([r, g, b])
plt.subplot(121);plt.imshow(img, cmap='gray', interpolation='bicubic')
plt.xticks([]);plt.yticks([])
plt.subplot(122);plt.imshow(img2, cmap='gray', interpolation='bicubic')
plt.xticks([]);plt.yticks([])
plt.show()
